Captain Fantastic gives Viggo Mortensen, the Lord Of The Rings star and frequent Cronenberg collaborator, a new challenge, playing Ben, a man who's spent a couple of decades in a cabin in Washington State raising six children in self-sufficient seclusion… until his wife's death sends the family on a road trip to New Mexico for her funeral - and a confrontation with the outside world.

Captain Fantastic has you working with half a dozen young actors, some of whom had never made a movie before. How did you figure each other out?

I was part of the final stage of casting, so I was able to read with the last two candidates for each [role]. That was probably as helpful to Matt [director Ross] as it was to me, because he could see how I would work with the kids. It was like some free rehearsals. And then we had a couple of weeks where we worked on the things we had to do together in the movie. We played a lot of music together, improvising and trying to get familiar. It's a nice way to get to know each other, non-verbally; there's a premium on listening, which is always great for an actor. By the end of that process we knew each other pretty well.

Ben isn't a conventional parent by any means, but the family dynamic he's created is impressive.

I mean, any family where the relationship is based on complete honesty and constant curiosity is a family that is on the way to showing mutual respect, you know. There's communication, and communication is one of the things we often find lacking - certainly in this country, as far as people being in different camps not even speaking to each other based on their region, based on their race, their political ideology, their religion, socioeconomic class, all kinds of reasons. And when you don't communicate, there's much more of a chance that you're not gonna understand each other, and not make progress as a society.

There's a limitation, though: Ben listens to his kids, but rarely to anyone else. The film makes a point of positioning him between his family and anyone else in the frame, and he does that with his words as well.

It's interesting. Probably the thing he's most opposed to in the world is rigidity, and inadvertently by being so morally uncompromising, he becomes rather rigid and closed off, which is the last thing he intended. He has to come to terms with that and find a way to evolve and find a new balance with his family. That's a great journey.